Anyone on here spraying nitrous with over 100 lbs of boost ?

VaOutlaw

VaOutlaw

King of the dyno
On my built 5.9 Cummins we are currently running 100 - 120 lbs of boost at the track and would like to start running some nitrous. I currently use it for spooling on the line but would like to start using it during the pass to lower my ET's and EGT's. What are your thoughts ?
 
Yeah back when we had a horrible flowing head, we used to be in the 125-130psi range and would spray. Now with a decent head we never see over 80psi, but we still spray.

Oh I doubt you will see any reduction in egt's. Might even make it warmer.
 
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Head has been fully worked and I have a Wicked Motorsports sheetmetal intake.

How much were you spraying with that much boost and how much did you pick up ?

Did spraying add any additional boost ?
 
If you dial back boost a bit and add more nitrous instead, you'll probably increase power....nitrous is 33% oxygen and air is only 21%, so the more nitrous you run, the more efficient it will be, all the way up until it starts backfiring or melting parts. Less drive pressure on the turbos frees up some power too.
 
small hijack, but what compression ratio are you big boost guys running?

also +1 on higher egt with n2o.
 
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VaOutlaw said:
Head has been fully worked and I have a Wicked Motorsports sheetmetal intake.

How much were you spraying with that much boost and how much did you pick up ?

Did spraying add any additional boost ?
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Sorry I am not going to say exactly what we spray, but it is more then some not as much as others. It is more then a casual shot.

Yes on fuel we only make ~70psi, on spray we make 75-78psi.
 
this may sound counterintuitive, but with my single and n20 I had to be much more aggresive with my gating on spray. As a result my boost drive ratio's were actually better on spray then fuel only, not a lot but better.
 
Subman631 said:
What is your drive pressure, that is what really counts?
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I was purposely not volunteering this information, but since it was asked for, as yes it tells you as much about it as anything does.

On fuel we see 70-75psi drive, Depending on how hard we spray anywhere from 75-115psi on our current setup. Previous head, wastegate, and cam setup when we were seeing 120-130psi overall boost, drive was always 150psi+ (gauge ends there so no idea but I would assume 200+). We make more power and less heat at 75psi then we ever did at 130psi+.

I am hoping with the upcoming season and our new head, cam, turbo's we will be down to mid 60's even on the spray, boost and drive. But we will have to see.
 
If I remember right, I think Banks saw power increases all the way down to sub-40psi on drive pressure. All that nitrous is pretty hard on CR pistons though.
 
gs1000 said:
small hijack, but what compression ratio are you big boost guys running?

I am running just over 16:1 compression

Subman631 said:
What is your drive pressure, that is what really counts?
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At this time I do not have gauges for drive pressure

gs1000 said:
Do you have a gate to bypass the large charger?
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The only gate I have is on my smaller turbo. It takes the drive pressure off my smaller turbo and vents it into charge pipe on my large turbo.
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VaOutlaw said:
gs1000 said:
small hijack, but what compression ratio are you big boost guys running?

I am running just over 16:1 compression



At this time I do not have gauges for drive pressure



The only gate I have is on my smaller turbo. It takes the drive pressure off my smaller turbo and vents it into charge pipe on my large turbo.
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thanks for the info, I thought the higher boost guys all ran lower compression than you 2 are, glad to see that it can be done with higher compression.
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Obviously the Cummins will make more boost and hence usually more drive pressure with an identical compound turbo set up on an 8 cylinder engine just do to the inherent head flow advantages of a V-8. I think many of us have found that reducing the boost a tad and really working on the tuning and gating to get the drive pressure to more closely mimic the boost pays good dividends on increased power and lower EGT's. I would highly recommend installing a drive pressure gauge before I did anything else.
 
gs1000 said:
bigger turbo eh?
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Not any bigger on the compressors, just a little more turbine. Not really looking for anymore power this off season, just looking to make it a little more efficient, and mostly focus on getting down to that 6000lbs weight limit.
 
Subman631 said:
Obviously the Cummins will make more boost and hence usually more drive pressure with an identical compound turbo set up on an 8 cylinder engine just do to the inherent head flow advantages of a V-8. I think many of us have found that reducing the boost a tad and really working on the tuning and gating to get the drive pressure to more closely mimic the boost pays good dividends on increased power and lower EGT's. I would highly recommend installing a drive pressure gauge before I did anything else.
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This.
 
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